1. Field of Invention
The invention relates to a capacitor structure and a method for forming the capacitor structure on a substrate.
2. Description of Related Art
Capacitors are one type of component commonly used in the fabrication of integrated circuits, for example in DRAM and other memory circuitry. A capacitor is comprised of two conductive electrodes separated by a non-conducting dielectric region. As integrated circuitry density has increased, there is a continuing challenge to maintain sufficiently high storage capacitance despite decreasing capacitor area. The increase in density has typically resulted in greater reduction in the horizontal dimension of capacitors as compared to the vertical dimension. In many instances, the vertical dimension of capacitors has increased.
One manner of fabricating capacitors is to initially form an insulative material within which a capacitor storage node electrode is formed. For example, an array of capacitor electrode openings for individual capacitors may be fabricated in such insulative capacitor electrode-forming material, with an example material being silicon dioxide doped with one or both of phosphorus and boron. The capacitor electrode openings may be formed by etching. It can be difficult to etch such openings within the insulative material, particularly where the openings are deep.
Furthermore, it is often desirable to etch away most if not all of the capacitor electrode-forming material after individual capacitor electrodes have been formed within the openings. Such removal enables outer sidewall surfaces of the electrodes to provide increased area and thereby increased capacitance for the capacitors being formed. However, capacitor electrodes formed in deep openings are often correspondingly much taller than they are wide, i.e., large aspect ratio features. This can lead to toppling of the capacitor electrodes, either (i) during etching to expose the outer sidewall surfaces, (ii) during transport of the substrate, and/or (iii) during deposition of the capacitor dielectric layer and/or outer capacitor electrode layer, among others. Techniques for providing structural support are required to be integrated with the fabrication of the capacitor electrodes to prevent the toppling of electrodes.